From: Eric Dumazet <eric.dumazet@gmail.com>
To: Vincent Li <vincent.mc.li@gmail.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: Disable tcp MSS option in three way handshake?
Date: Fri, 26 Oct 2012 00:42:28 +0200 [thread overview]
Message-ID: <1351204948.6537.263.camel@edumazet-glaptop> (raw)
In-Reply-To: <CAK3+h2xKHBNXzY0WNwPV+oGbY00UVfJpO-qjFW2cxCpmdt+hAg@mail.gmail.com>
On Thu, 2012-10-25 at 15:27 -0700, Vincent Li wrote:
> Hi,
>
> this sounds crazy, we have a weird situation that an unknown tcp
> implementation not putting tcp MSS option in the SYN/ACK which caused
> us some issue. I am tasked to mimic the unknown tcp immplementation on
> not sending MSS in tcp SYN/ACK, I am wondering if I can achieve that
> by modifying linux kernel tcp code, there is socket option
> TCP_MAXSEG, but that seems only affecting the size of MSS, not
> removing the MSS option. do you have any pointer on how to do that in
> kernel tcp code?
You'll have to patch the code.
Or else, you could add a new feature to net/netfilter/xt_TCPMSS.c
(We already have
#define XT_TCPMSS_CLAMP_PMTU 0xffff
You could add
#define XT_TCPMSS_REMOVE 0xfffe
and replace MSS option by NOP
next prev parent reply other threads:[~2012-10-25 22:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 22:27 Disable tcp MSS option in three way handshake? Vincent Li
2012-10-25 22:42 ` Eric Dumazet [this message]
2012-10-25 22:52 ` Vincent Li
2012-10-25 23:15 ` Vijay Subramanian
2012-10-26 22:54 ` Vincent Li
2012-11-04 0:25 ` Jan Engelhardt
2012-10-25 22:50 ` Rick Jones
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